1. Field of the Invention
The present invention relates to an apparatus for fabricating a semiconductor device and its cleaning method, and more particularly to an apparatus for fabricating a semiconductor device suitable to clean effectively even the shadow area of a reaction chamber, such as the lower space of a susceptor where a plasma is hardly formed, and its cleaning method.
2. Description of the Background Art
Recently, an in-situ plasma cleaning is widely used as a method for cleaning the inside of the reactive chamber of an apparatus for fabricating a semiconductor device and of a chemical vapor deposition (CVD) equipment. In this method, in order to remove a contaminant particle generator attached inside the reactive chamber, an etching gas, instead of a process gas, is flew into the reactive chamber, to which a plasma electric power is applied to activate it, thereby etching the inner wall of the reactive chamber weakly. As the etching gas, a gas containing chlorine or fluorine is typically used.
FIG. 1 is a schematic view of an apparatus for fabricating a semiconductor device in accordance with a conventional art, based on which the in-situ plasma chamber cleaning will now be described.
As shown in the drawing, a reactive chamber 10 includes an upper container 10a and a lower container 10b which are flange-coupled. An O-ring 20 is inserted at the flange portion for an effective sealing. The lower container 10b of the reactive chamber is grounded and has an inlet and an outlet (not shown). The upper container 10a of the reactive chamber is formed in a dome shape, so that the gas injected into the reactive chamber 10 is evenly dispersed and distributed on a susceptor 40.
With respect to the general CVD chamber in the dome shape, the dome is made of an insulation material such as quartz or ceramic. In this respect, since the plasma electrode 30 is installed outside the upper container 10a of the reactive chamber, encompassing the upper container 10a of the reactive chamber, it is also formed in a dome shape. The reason why the plasma electrode 30 has a dome shape is to enlarge the effective area of the plasma electrode to heighten the density of the plasma.
An RF electric power generated by an RF generator 60 is controlled by a matching box 65 to have a minimized reflectance and supplied to the plasma electrode 30.
A wafer 50 is mounted on the susceptor 40 which is installed inside the reactive chamber 10. The susceptor 40 is grounded to serve as an opposite electrode to the plasma electrode 30.
After a plasma forming gas is injected into the reactive chamber 10 through the gas inlet (not shown), when the RF electric power is applied to the plasma electrode 30, a plasma 70 is formed between the susceptor 40 and the plasma electrode 30.
In the aforementioned semiconductor device fabrication apparatus, when the CVD process is performed, a thin film is formed at the upper surface of the wafer 50, and at the same time, a contaminant film is deposited at the wall face in the chamber.
In case where the contaminant film deposited on the wall face of the chamber is cleaned by plasma dry etching of FIG. 1, the following problems arise.
First, the upper container 10a of the reactive chamber is made of metal according to circumstances. In this case, even though the RF electric power is applied to the plasma electrode, the plasma 70 is not properly formed on at the upper portion of the susceptor 40 due to a shield effect of the upper container 10a. 
Secondly, since the plasma electrode is installed at the outer wall of the upper container 10a, the plasma is generated only at the upper portion of the susceptor 40. That is, geometrically, the plasma could be hardly generated at the lower portion of the susceptor 40. Thus, since the plasma is not generated at the lower portion of the susceptor 40, it is not possible to clean the lower space of the susceptor 40 with plasma. Thus, a supplementary process is further required to clean the lower space of the susceptor 40.
Thirdly, since the upper space of the susceptor 40 is comparatively large, a very intense RF electric power must be applied to make a clean by dry etching the inner wall of the reactive chamber 10a with plasma. In this case, however, some parts therein are inevitably over-etched.
Therefore, an object of the present invention is to provide an apparatus for fabricating a semiconductor device that is capable of cleaning at one time the whole reactive chamber by forming a plasma even at the shadow area, such as the lower space of a susceptor, at which it is difficult to form a plasma, and its cleaning method.
Another object of the present invention is to provide an apparatus for fabricating a semiconductor device that is capable of easily controlling the strength of a plasma by adjusting the size of a reactive space where a plasma is formed by shifting a susceptor vertically without increasing or decreasing an RF electric power, and its cleaning method.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided an apparatus for fabricating a semiconductor device including: a reactive chamber having an inlet and an outlet for a gas and being electrically grounded; a susceptor installed in the reactive chamber for mounting a wafer thereon and being electrically insulated with the reactive chamber; and an RF generator for applying an RF electric power to the susceptor.
In the apparatus for fabricating a semiconductor device of the present invention, it is preferred that the susceptor is movable in the vertical direction of the face of the wafer.
In the apparatus for fabricating a semiconductor device of the present invention, the reactive chamber may be made of a metal, of which upper portion is preferably formed in a dome shape.
In order to reduce a plasma induced damage, the apparatus for fabricating a semiconductor device of the present invention may further includes: a remote plasma generator installed outside the reactive chamber; and a plasma transfer pipe for connecting the remote plasma generator and the reactive chamber to transfer the plasma generated from the remote plasma generator to the reactive chamber.
The apparatus for fabricating a semiconductor device may further include a heating unit for heating the reactive chamber to thereby heighten a cleaning effect.
To achieve the above objects, there is also provide a method for cleaning the apparatus for fabricating a semiconductor device including the steps of: injecting a plasma forming gas through the gas inlet; and moving the susceptor in the vertical direction of the face of the wafer while applying the RF electric power to the susceptor, to control the position and the density of the plasma.
The cleaning method of the present invention may further include the steps of: applying the RF electric power; generating a plasma of a gas containing fluorine containing gas component by the remote plasma generator; and transferring the plasma of the gas containing a fluorine component through the plasma transfer pipe to the reactive chamber.
The gas containing a fluorine component comprises SF6 gas or NF3 gas.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.